# Homework Help: Pipe Discharge and Diameter

1. Mar 7, 2016

### vinamas

1. The problem statement, all variables and given/known data
An engineer is planning for a network of pipes to a residential tower containing 360 apartments each one of them consumes 0.05 liters/s of water what is the least possible pipe discharge for the main pipe in the network
if the fastest speed of discharge in the pipe is 4m/s then what is the least diameter possible that doesn't cause leaking

2. Relevant equations
J=Av=V/t

3. The attempt at a solution
I convert from liters to volume try to apply the law of course it doesn't work I have two variables

my work:
360*0.05*10^-3/s=A*4
A=0.0045
0.0045=(d/2)^2*pi
d=0.07m. I think the 360 apartments are vital to solve this problem but I don't know where to use them
the diameter is 0.2m How do I get this answer????

Last edited by a moderator: May 7, 2017
2. Mar 7, 2016

### BvU

0.05 l is a shot glass. Is this per year ?

Could you list off the relevant equations a bit more completely ?

3. Mar 7, 2016

### vinamas

o
Oh sorry I just edited it its liters per second

4. Mar 7, 2016

### BvU

Can you show your work ?
And how do you find the 0.05 l/s ?

5. Mar 7, 2016

### vinamas

its given in the problem

my work:
360*0.05*10^-3/s=A*4
A=0.0045
0.0045=(d/2)^2*pi
d=0.07m. I think the 360 apartments are vital to solve this problem but I don't know where to use them

6. Mar 7, 2016

### BvU

360 is the number of users; 4 is m/s I suppose. You get 7.6 cm diameter.

But don't most of these 360 users sleep around the same time and wake up around the same time and want to shower at approximately the same time ? Would they be happy with 3 liters/minute each ?

7. Mar 7, 2016

### vinamas

Well thats the question lol

8. Mar 7, 2016

### vinamas

So what is wrong about my method?

9. Mar 7, 2016

### BvU

No idea what's wrong. I calculate what you calculate, but it is highly unlikely that's really what is asked. I also don't understand the mentioning of leaking in the problem statement.
Nor, in fact, the "least possible pipe discharge for the main pipe in the network" ? (even before the 4 m/s is provided).

Any clue in your notes/textbook ?

10. Mar 7, 2016

### vinamas

You can forget those details the diameter of the main pipe is what the question asks I know its confusing